The purpose of this research study is to test two medicines for migraine prevention in children and adolescents. The investigators want to see if amitriptyline and/or topiramate are better than placebo (sugar pill) in reducing headache frequency in children and adolescents ages 8 to 17 with migraines. At this time, there are no FDA approved medicines approved in the US for the prevention treatment of migraine headaches in children and adolescents.